The possible risk of Guillain-Barré syndrome from influenza vaccines remains a potential obstacle to achieving high vaccination coverage. However, influenza infection might also be associated with Guillain-Barré syndrome.
A study has assessed the risk of Guillain-Barré syndrome after seasonal influenza vaccination and after influenza-coded health-care encounters.
Researchers have used the self-controlled risk interval design and linked universal health-care system databases from Ontario, Canada, with data obtained between 1993 and 2011.
Researchers have identified 2831 incident admissions for Guillain-Barré syndrome; 330 received an influenza vaccine and 109 had an influenza-coded health-care encounter within 42 weeks before hospitalisation.
The risk of Guillain-Barré syndrome within 6 weeks of vaccination was 52% higher than in the control interval of 9-42 weeks ( relative incidence 1.52 ), with the greatest risk during weeks 2-4 after vaccination.
The risk of Guillain-Barré syndrome within 6 weeks of an influenza-coded health-care encounter was greater than for vaccination ( 15.81 ).
The attributable risks were 1.03 Guillain-Barré syndrome admissions per million vaccinations, compared with 17.2 Guillain-Barré syndrome admissions per million influenza-coded health-care encounters.
The relative and attributable risks of Guillain-Barré syndrome after seasonal influenza vaccination are lower than those after influenza illness.
Patients considering immunisation should be fully informed of the risks of Guillain-Barré syndrome from both influenza vaccines and influenza illness. ( Xagena )
Kwong JC et al, The Lancet Infectious Diseases 2013; 13: 769-776